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    <meta charset="UTF-8">
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    <title>Document</title>
</head>
<body>
    <h1>jsonp</h1>
    <button id="btn">发送jsonp请求</button>
    <script>
        function callback(data){
            console.log(data);
        }
        const oBtn = document.getElementById('btn');
        let oScript= null;
        oBtn.onclick=function(){
            if(oScript){
                oScript.remove();
            }
            oScript = document.createElement("script");
      oScript.src = "http://127.0.0.1:3030/getUser?userId=001&cb=callback";
      document.body.appendChild(oScript)
        }
    </script>
</body>
</html>